In a cellular communication, a cell identity (ID) is used to identify a cell that is served by a base station (BS). By means of the cell identity, a terminal device can detect the cell and further be connected to the cell. By way of example, in a third Generation Partnership (3GPP) Long Term Evolution (LTE) network, a cell is assigned to a physical cell identity (PCI), which is a layer 1 cell identity. The PCI is carried in a synchronization signal and broadcast by the BS serving the cell such that the terminal device may detect the PCI and further establish communication with the cell. In particular, during a cell selection/reselection, the terminal device can identify neighbor cells through corresponding cell identities. As used herein, the term “cell selection/reselection” refers to a procedure during which the terminal device selects a suitable cell to camp on in response to, for example, being powered on, leaving a “flight” mode, moving between a plurality of cells, and so on. The term “neighbor cells” refers to at least two cells that are adjacent to and overlap each other.
In the 3GPP LTE network, an eNB is deployed by an operator, and one operator may deploy a number of eNBs in a network. Furthermore, an eNB has three cells. However, there are only about five hundred PCIs available, which is far less than the number of deployed cells. Accordingly, the PCIs have to be reused, which may cause a problem of cell identity collision and/or cell identity collision. As used herein, the term “cell identity collision” refers to a scenario where two neighbor cells use the same cell identity, and therefore the terminal device cannot distinguish the two cells and have access to either of them. The term “cell identity confusion” refers to a scenario where two neighbor cells of a specific cell use the same PCI and the terminal device cannot successfully be handed over to an appropriate one of the two neighbor cells while moving.
In order to ensure a success of the cell selection/reselection, the cell identity collision and confusion have to be avoided. Conventionally, the cell identity collision and confusion may be avoided by assigning distinguishing PCIs to the neighbor cells and the neighbor cells of a specific cell. Such assignment may be implemented through radio network planning of the operator.
Recently, unlicensed spectrums have become efficient complements of licensed spectrums exclusive to individual operators in order to meet an increasing demand for wireless broadband data. The unlicensed spectrums may be shared among a plurality of operators. Accordingly, a plurality of BSs from different operators may operate in a same carrier frequency. In this case, among the BSs of different operators, the problem of the cell identity collision and confusion may also occur. However, in a conventional approach, an operator separately deploys its own cells. Thus, it is very difficult to avoid the problem through the radio network planning.